System and method for supporting quality of service in vertical handovers between heterogeneous networks

ABSTRACT

A method, system, and business model are disclosed for supporting handover between a mobile host and a corresponding node located in a heterogeneous network. Handover paths are established to accommodate a plurality of quality of service properties. Admission control is performed that considers the established handover paths and an established first reservation path. Gateways are contacted to determine a handover path to use. The determined handover path is used to support vertical handover. A second reservation path is established while maintaining the first reservation path and the handover path.

FIELD OF THE INVENTION

The present invention relates generally to telecommunication systems andmore particularly to supporting quality of service with verticalhandoffs in wireless mobile telecommunication systems.

BACKGROUND

Recent years have witnessed an explosive growth of mobile computing andthe emergence of new wireless technologies. The desire to be connectedany time, any where and in any way, leads to an increasing array ofheterogeneous systems, application, devices and operators. Suchheterogeneity is not likely to disappear in the foreseeable futurebecause the variety of application requirements makes it difficult tofind an optimal and universal solution. Likewise, an eagerness tocapture the market encourages competing organizations to releasenon-interoperable systems. As a result, the ability to provide seamlesstelecommunication services in such a heterogeneous environment may beimportant to the success of the next generation of mobile communicationsystems.

Mobile IP is a current standard for supporting mobility in IP networks.Mobile IP defines a home agent and a foreign agent. The packets destinedfor a mobile host are intercepted by the home agent and tunneled to theforeign agent. The foreign agent de-capsulates the packets and forwardsthem directly to the mobile host. Mobile IP may provide a framework forallowing users to roam outside the home networks without disruption totheir applications. However, known Mobile IP protocol networks are builtwith the wired Internet in mind where the end host's mobility is limitedand infrequent. Furthermore, the Mobile IP protocol does not utilizenetwork topology information and produces global updates whenever localmobility occurs, e.g., mobility between adjacent base stations in thesame administration domain. Likewise, Mobile IP has no support forquality of service (QOS) features, such as high bandwidth requirements,high reliability requirements, and the like.

Mobile IP does not support QOS because it treats different forms ofmobility uniformly, and produces a new care-of-address for everyhandover from one base station to another. Therefore, a user moving ashort distance, e.g., between two adjacent base stations in the sameadministration domain, can experience significant disruption, e.g., lossand/or delay of signal, due to the frequent registration to the remotehome agent. Likewise, creating a new care-of-addresses for everyhandover introduces complexity and delay for a new QOS reservation orpath setup.

Known solutions include Cellular IP, Hawaii and other micro-mobilityrelated protocols. Such protocols attempt to limit the global updatesbecause of local movement by either introducing hierarchical foreignagents or smart foreign agents depending on the network topology. Butthe known schemes are based on homogeneous networks and the sameadministration domains. In other words, the known schemes attempt tosolve the horizontal handover problems but do not address verticalhandover, e.g., handovers between base stations under differentadministration domains. When vertical handover occurs, known schemes nolonger work because no common agent exists above two separateadministration domains. When vertical handover occurs, the mobile agentneeds to rely on the Mobile IP to resolve macro-mobility issues. Toenable seamless service, QOS capabilities should be provided duringvertical handover.

RSVP is the current standard for supporting Inte-Serv in an IP network.It is known that to provide guaranteed service, reservation or admissioncontrol is needed at the edge router regardless of the QOS mechanismused in the core network. RSVP or its extension is a popular signalingprotocol used by a host to request specific QOS capabilities from thenetwork for particular application data streams. RSVP is also used byrouters to deliver QOS requests to all nodes along the path of the datastreams and to establish and maintain a state to provide the requestedservices.

A second set of protocols includes MRSVP, RSVP-A and other modificationsto the RSVP signaling protocol. Because the RSVP protocol is designedwithout the consideration of mobility by its receiver-initiatingalgorithm, MRSVP and its relatives are proposed to support mobility.These protocols are based on proactively set up reservations, however,in base stations where the application is likely to travel. Suchproactive reservation could lead to bandwidth waste due to the largeamounts of control messages needed to refresh the RSVP soft states.

Micro-mobility protocols only deal with mobility issues and have nointrinsic QOS support. This problem can be addressed to some extent byusing a common agent and reusing the common network path before andafter handover. The previous reserved path could be reused and QOSreservation and update information could be limited to local network.But the lack of QOS support during the handover period still exists.When the terminal moves from one base station to other base stations,packets in the previous base station are either dropped or forwarded tothe new base station without QOS support. Micro-mobility protocolsattempt to decrease packet loss but other QOS parameters such asbandwidth and delay are not considered. Likewise, no differentiationexists between the treatments of different applications. Differentapplications have different QOS parameters in terms of bandwidth, delayand loss so they are divided into QOS classes and receive differentiatedservice based on their classes. But known handover schemes treatapplications the same which violates the philosophy of differentiationand may lead to unnecessary system overuse.

As discussed above, when vertical handover occurs, micro-mobility andits related QOS improving extensions could not be used because of thelack of common agent and common network path. Schemes such as RSVP,MRSVP and RSVP-A which produce global updates and introduce longerhandover periods can be used. A problem occurs regarding how to provideQOS support during this handover period.

Moreover, the upper-layer adaptation ability could also be taken intoaccount when adopting network layer QOS support. Since adaptationability is a basic requirement for elements working in the mobiledomain, the application, middleware, and transport layer are equippedwith some degree of adaptation mechanisms to deal with the packet lossor delay. Without the consideration of the upper-layer's adaptationability, IP layer handover adaptation may unnecessarily duplicate themechanism or even deteriorate the upper-layer's performance.

To enable seamless communications, there is a need for a QOS supportsystem to support vertical handovers caused by mobile terminals.

BRIEF SUMMARY

A system and method are disclosed to support vertical handover betweenheterogeneous networks. To accommodate handover, an access routercontacts a gateway specializing in supporting QOS during the handover.Paths with different QOS properties are configured among peer handovergateways. Thereafter, the gateway determines the correspondingdestination handover gateway and chooses the path most suitable for thecurrent handover requirements of applications. If no such path isavailable or the path is congested because of too much handover traffic,the handover is handled in an alternate way, such as in a best-effortfashion.

The handover gateways and related configured handover paths can beorganized in different ways. One way is that each operator maintainstheir own gateway and sets up handover contracts with adjacentoperators. As the number of operators increase, the scheme may becomeharder to manage. In another way, a hyper operator builds a specializedhandover network and utilizes bi-lateral contracts with main operatorsto employ specialized gateways and handover paths. When handover occurs,the gateway in each domain contacts the hyper operator's overlay networkto accomplish the handover process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an exemplary communicationssystem for implementing the quality of service support system.

FIG. 2 is a block diagram illustrating a network architecture supportingQOS handover in which operators have contract with adjacent operatorsand no intermediate hyper operator is present.

FIG. 3 is a flow chart describing a handover process.

FIG. 4 is a flowchart illustrating exemplary reservation, admissioncontrol and choice of handover path according to the quality of servicerequirements of the application.

FIG. 5 is a block diagram illustrating a network architecture accordingto the quality of service support system including a hyper operatoroverlay network.

DETAILED DESCRIPTION

A quality of service (QOS) support system and method are described thataddress horizontal and vertical handovers, and particularly addressesvertical handover among different administrative domains, e.g.,operators. Horizontal handovers include handovers between base stationsthat are using the same type of wireless network interface. Verticalhandovers can include handovers between base stations under differentadministration domains. Other vertical handovers can be addressed suchas handovers between different wireless network technologies, handoversbetween heterogeneous terminals, and handovers between heterogeneousapplications for the same task. A business model of hyper operator canconstruct a specific handover network together with related AAAmechanisms. The hyper operator can obtain contracts with relatedoperators and perform the handover for the related operators.

FIG. 1 is a block diagram of an exemplary communications system 100 forimplementing the QOS support system. The communication system 100includes a communication network 110. The communications network 110 caninclude networks such as a cellular network, satellite networks, localarea networks (LAN) and Bluetooth networks. The communications system100 may also include a mobile host 120 and an end device 130. The mobilehost 120 may allow a user to access the end device 130. Typical mobilehosts 120 include a laptop computer, a mobile phone, such as a cellularphone, a personal digital assistant (PDA) or other mobile devices usedto interface with end device 130 via the communications network 110.Typical end devices 130 include a desktop computer, a laptop computer,telephones, such as cellular phones, a PDA or other devices.

FIG. 2 is a block diagram illustrating a network architecture thatsupports QOS handover where network operators have contract withadjacent operators and no intermediate hyper operator is present. TheQOS support system 200 includes various administration domains, such asDomain one 202, Domain two 204 and a third domain, such as the Internet206. The Internet 206 includes MPLS paths which are pre-configured byrelated administration domains after neighborhood information iscollected. Administration domains 202, 204 and 206 contain informationregarding the neighboring administration domains so that defined MPLSpaths can be used. The QOS support system 200 allows a user of themobile host 120 to communicate with the end device such as correspondingnode (CN) 222.

The QOS support system 200 interacts with administration domains andprovides necessary monitoring, signaling and maintenance functions tohelp guarantee QOS support during a vertical handover and new pathreservation period. Regarding FIG. 4, described below, the QOS supportsystem in FIG. 2 includes a distributed architecture without a hyperoperator overlay network.

Referring to FIG. 2, a handover gateway (HO-GW) 208 is introduced in theadministration domains 202, 204 to administer traffic during thevertical handover. A Multiprotocol Label Switching (MPLS) protocol, orthe like, is used to arrange defined QOS paths between theadministration domains 202, 204. Different MPLS paths having differentQOS properties may be used to allow for the various treatment ofhandover traffic based on the application requirements.

Domain one 202, Domain two 204 and the Internet domain 206 also includeother telecommunications components such as routers (R) 210 and antennasor access points (AP) 212. The Internet 206 routers include gateway (GW)routers 214 that connect to the foreign agent (FA) gateway (GW) routers216 of Domain one 202 and Domain two 204. The routers also includeaccess routers (AR) 218 that can be accessed by antennas or accesspoints (AP) 212 and that can be accessed by other components such ashome agent 220. The corresponding node (CN) 222, e.g., the communicationpeer of mobile host, can access the Internet domain 206 via otherrouters, such as an edge router (ER) 224.

Differentiated services (Diff-serv), a known QOS technology, MPLS andRSVP protocols, or other similar applications, can setup paths betweenthe routers. Because of the scalability and traffic engineering ability,MPLS techniques can be used in the Internet 206 to set up the handoverpath with different QOS properties. Other techniques could also be used.By way of example, two MPLS paths M1 and M2 can be established betweenDomain one 202 and Domain two 204. Depending on the applications'requirements, either M1 or M2 could be used. The MPLS supports trafficengineering and tunneling and allows for communication frameworks whichare scalable and suitable to implement in the core network. Trafficengineering is used to distribute the traffic to different pathsaccording to current network traffic load. Tunneling is used to overlaythe packets to a new destination by wrapping the packet in anotherpacket.

Vertical handovers usually occur in an area where two networks havecommon coverage, known as an overlay area 226. Vertical handovers canoccur when users actively choose an access network based on the user'sown needs and can also occur in accordance with contracts with theservice providers. The user's needs may include application QOSrequirements, such as cellular networks for telephony and wireless localarea networks (WLAN) for multimedia streaming. Other needs may includecost, security, and the like. Heterogeneous networks exist toaccommodate the different needs of the user.

Vertical handover also may occur due to the limitations on accessnetwork coverage. Users change access systems when at the edge of acoverage area of an access network. When the user is located in theoverlay area 226, the user can switch to another access network usingvertical handover. If the user is not located in the overlay area 226,the user could lose the connection. When disconnection occurs, thesession is either reset or software may attempt to compensate in otherways, such as using different coding schemes to recover the losses frompackets already received.

The Internet protocol (IP) is a common network layer to connectdifferent administration domains and the Internet 206. The Internet 206includes some QOS support such as MPLS. Macro-mobility which may not behandled by described framework due to a lack of handover paths betweenoperators, may be handled by standard Mobile-IP protocols. Theadministration domains include versions of the micro-mobility algorithmsuch as HAWAII, Cellular IP, and the like, to help guarantee the QOSduring horizontal handover and MPLS paths within the network.

The corresponding node (CN) 222 uses a mobile-IP communication protocolto communicate with the mobile host (MH) 120. The home agent (HA) 220includes functions, such as via software, to support a multiple pathreservation. The reservation is accomplished by the home agent (HA) 220via the RSVP protocol. The Mobile IP protocol is used to route thepackets, but without QoS support, and protocols such as RSVP, Diff-Servor MPLS are used to set up the QoS support. Domain one 202 and Domaintwo 204 include handover gateways (HO-GW) to accommodate the verticalhandover QOS. QOS between the handover gateways (HO-GW) and accessrouters are accomplished by domain-specific QOS mechanisms. Access point(AP) 212 includes layer 2 QOS mechanisms also according to differentunderlying layer 2 technologies such as 802.1Q/D and Subnet BandwidthManager (SBM) for the LAN.

MPLS paths M1 and M2 with defined QOS properties accommodate end-to-endQOS handling during vertical handover. The handover gateways (HO-GW) 208for Domain one 202 and Domain 2 204 establish the MPLS paths M1 and M2.For the administration domains, handover gateways (HO-GW) 208 can beorganized in a hierarchical manner where multiple band-over gatewaysHO-GW in the administration layers of one domain can be involved insetting up the handover path depending on the network topology andhandover traffic patterns. The handover gateways (HO-GW) 208 areresponsible for handover traffics of the multiple access routers (AR)218. For access routers (AR) 218 near the overlay area with networks ofanother administration domain, more vertical handovers can occur via thehandover gateway (HO-GW) 208. Without a centralized operator such asHyper Operator described later, the handover gateways (HO-GW) 208 ineach administration domain identifies adjacent handover gateways ofother operators. By logging the mobility pattern of its client over aperiod of time and examining the client's next operator after handover,the adjacent handover gateway information can be derived. Once theadjacent handover gateways are identified, MPLS paths can beestablished.

FIG. 3 is a flow chart describing a handover process. At block 300, aninformation gathering process begins such that whenever a verticalhandover occurs, the access router (AR) 218 informs a supervisinghandover gateway (HO-GW) 208 of the destination administration domain,e.g., Domain one 202 or Domain two 204. A link layer mobility managementalgorithm could supply the access router with the destinationadministration domain information. At block 310, upon receiving theinformation, the handover-gateway (HO-GW) 208 queries a neighborhooddatabase to determine whether the database includes the administrationdomain and MPLS paths have been established. At block 340, if theadministration domain is included and the MPLS has been established, thevertical handover can occur. At block 350, otherwise, the information isadded to the database according to an updating algorithm so that theinitialization process of the new MPLS paths for the next verticalhandover could be served. Because each access router can only overlay alimited number of networks, only several rounds may be needed for thehandover-gateway (HO-GW) 208 to complete the learning to have fullfunctionalities.

Thus, the handover gateways (HO-GW) 208 can learn and updateneighborhood databases and establish MPLS paths (M1 and M2 are used onlyas an example, multiple paths could be established based on therequirements) having different QOS parameters to each neighboringnetwork. The handover gateway (HO-GW) 208 can also communicate withother handover gateways (HO-GW) in the same administration domain toaccommodate performance and scalability. The handover gateway (HO-GW)208 monitors and maintains the MPLS paths and reports related QOSparameters to the access routers (AR) 218 to achieve new admissioncontrol algorithms. The handover gateways (HO-GW) 208 can also handlesignaling and tunneling tasks to begin and end handover traffics.

Standard MPLS procedure can be used to setup the routers, for example,to choose the correct QOS classes, application QOS requirement, such asreal-time or not real time, and differentiated handover QOSrequirements. The handover QOS requirements may be influenced by theapplication QOS requirements. According to Internet protocol 2 (IP2),handover is classified as fast handovers, smooth handovers and seamlesshandovers. Other types of handovers include a high-bandwidth handover. Afast handover is a handover that can satisfy strict delay bounds, forexample, real-time services. A smooth handover is a handover that canminimize a loss of packets. And seamless handover is a handover withminimum perceptible interruption of the services.

MPLS allows for a fine granularity in terms of QOS parameters, thusmultiple paths can be established to obtain finer control of handoverqualities and obtain a good balance between performance, price andcomplexities. Some of the QOS parameters influencing applicationsinclude delay, loss and bandwidth, which can be accommodated bycombinations of the fast handover, smooth handover, high-bandwidthhandover and seamless handover.

To support vertical handover, the access router (AR) 218 determines whatkind of service the application of the mobile host (MH) 120 requiresduring the handover. The determination can be achieved in differentways. For example, the application could inform the access router (AR)218 of the information at application initialization based on theapplication requirements and its adaptation ability above the IP layer,for example, adaptation ability in the transport layer, applicationlayer, or any other layer above IP layer. In addition, the access router(AR) 218 can derive the information by examining flow port fields. In anIP packet header, the port field is used to show what upper layerprotocol is used in this packet, i.e., application category information.Examination of the flow port fields allows for application transparency,but can achieve less accurate information than if the information weredetermined from the application.

After the paths are set and the access router receives a verticalhandover service requirement, the paths can be used in several ways. Thepaths can be used to forward residue packets from a current access point(AP) 212, for example one that is located in Domain one 202, to a newaccess point (AP) 212, for example one that is located in Domain two204, after handover occurs. The paths can also be used to forward newpackets from the current access point (AP) 212 to the new access point(AP) 212 during the period of a new reservation between thecorresponding node (CN) 222 and the new access point (AP) 212. If a newreservation cannot be achieved quickly, the path can be used to forwardthe packets until a new reservation is achieved or the session isterminated.

FIG. 4 is a flowchart illustrating exemplary reservation and admissioncontrol according to the QOS support system. The mobile host (MH) 120can include an application that accomplishes the reservation andadmission control. The reservation path could occur via the linksbetween mobile (MH) 120 and the home agent (HA) 220 and the linksbetween home agent (HA) 220 and corresponding node (CN) 222. Byexamining how the QOS is supported before and after a vertical handover,the application runs in different phases.

A first phase includes the time before the handover in which theapplication typically operates. QOS support in this phase is achievedthrough maintained RSVP paths established by traditional RSVP protocols.A second phase includes the period from the time when handover isdetected in original base station to the time when the new RSVP path isestablished to the new base station. During this time period, the RSVPpath of the first phase and the selected configured MPLS path operatetogether to guarantee QOS support to the application. A third phaseincludes the period when the reservation path of the first phase and theMPLS handover path are released, and only the newly established path isused for the traffic that follows. After the third phase, theapplication can enter the first phase and begins regular operationagain.

At block 400, RSVP messages are used to provide the access router (AR),also the admission control point, 218 with the application's QOSrequirements during the non-handover operation phase. The RSVP messagesincluding information such as desired QOS (RSPEC), trafficcharacteristics (TSPEC) and flow differentiation (FILTER_SPEC). At block410, the access router (AR) 218 is provided with application's QOSrequirements of the second phase, e.g. the requirements during thehandover. Because mobile computing software can vary, to help guaranteeservice, a service loss profile, vertical handover service requirements,and probability of seamless communication factors can include thefactors used to express the adaptive QOS requirements during thetranslation.

At block 420, a configured MPLS path is selected in accordance with thespecified handover QOS requirements. The access routers (AR) 218 can beused to determine particular MPLS paths such as M1 or M2 suitable forthe application using the information factors described above. Currenttraffic loads on the MPLS paths M1 and M2 can also be considered.Monitoring and reporting functions of the handover gateway (HO-GW) 208can report the traffic load.

At block 430, admission control is used to determine whether to acceptthe application's reservation or not. The received handover requirementsare used to help determine whether or not to accept the reservation. Forexample, an admission control algorithm could be used that includes thedelay on the selected MPLS path in the calculation of end-to-end delaybounds regardless of whether the path is used for a vertical handover.Other, less conservative, algorithms could be used, such as algorithmsbased on stochastic models to produce more accurate system usageinformation. At block 440, if the reservation is not accepted, thereservation is terminated and resubmitted later as needed.

At block 450, if the reservation is accepted, when vertical handoveroccurs between the mobile host (MH) 120 and the corresponding node (CN)222, the vertical handover is supported through the configured MPLSpaths. The new RSVP reservation is carried on from corresponding node(CN) 222 to the mobile host (MH) through the new paths to the newnetwork. During the process time (the handover time), the QOS support isguaranteed until a new reservation is completed.

The QOS support system uses the above-described path setup process andadvanced admission control process to achieve QOS support duringvertical handover. The mobile host (MH) 120 is located in an overlayarea 226 of Domain 1 and domain 2. A QOS support system algorithm isinitiated by a domain, e.g., Domain 1. The application sends therequired QOS parameter to the access router in domain 1. The accessrouter contacts its supervised handover-gateway (HO-GW) to determinewhich MPLS path can accommodate the application. After admission controlsucceeds, path 1 is set up between the mobile host and the correspondingnode (CN) 222. The reservation process runs on top of the Mobile IP,e.g., an IP—IP tunneling QOS support is used.

When the mobile host (MH) 120 switches to Domain 2, vertical handoveroccurs. After the mobile host (MH) 120 passes the authentication andauthorization procedures in Domain 2, the Domain 2 access router informsthe handover gateway (HO-GW) 208 located in Domain 2, which in turncontacts the handover gateway (HO-GW) 208 located in domain 1 toestablish a tunnel between the access routers located in Domain 1 andDomain 2. The tunnel uses the selected MPLS paths so that the end-to-endQOS requirements are followed. The access router (AR) 218 located inDomain 2 renegotiates the path between the mobile host (MH) 120 and thecorresponding node (CN) 222. During setup, new packets continue to besent to the Domain 1 access router and then tunneled to the Domain 2access router (AR) 218.

When the setup of the new path is complete, if the admission controlsucceeded, a router, e.g., the last router accomplishing the admissioncontrol can send a confirmation message, such as a RESVconf message, tothe Domain 2 router to reserve the path. The router can also send amessage to the Domain 1 router to disconnect the old path, e.g., such asa RESVtear message. Upon receiving the RESVtear message, the Domain 1access router completes the packets in the access router's buffer andinforms the Domain 1 handover gateway (HO-GW).

If the admission control fails, the RESVtear information is returned tothe Domain 2 access router. The Domain 2 access router can then handlethe call in accordance with a defined policy or applicationrequirements. Domain 2 can continue to use the tunnel between the newaccess router and attempt to renegotiate the reservation, e.g., after atime delay, to try to gain admission control. The Domain 2 access routercan negotiate with the Domain 1 access router (AR) 218 about how longthe tunnel is maintained. The Domain 2 access router (AR) 218 can alsonegotiate with the mobile host about how the adaptation can occur.Because the connection is maintained, QOS support is used during thisprocess too.

FIG. 5 is a block diagram illustrating a network architecture accordingthe QOS support system 500, where the architecture includes a hyperoperator overlay network (HO-OL) 510. The hyper operator overlay network(HO-OL) can exist in the Internet domain 206 which interacts with therelated gateways in the administration domains, e.g., Domain one 202 andDomain two 204. The hyper operator overlay network (HO-OL) 510 canreduce the number of tasks performed by the handover gateway (HO-GW) 208in the administration domains. The hyper operator overlay network(HO-OL) 510 can control several functions, such as, establishing theMPLS paths, monitoring and maintaining the traffic in the MPLS paths M1and M2, and cooperating with the access router (AR) 218 to perform theadmission control. The handover gateway (HO-GW) 208 would thenadminister local optimization, such as by providing QOS support in theadministration domain.

Because the hyper operator overlay network (HO-OL) 510 has globalknowledge of each administration domain, optimal vertical handoverperformance could be achieved. The hyper operator overlay network(HO-OL) 510 can interact with related routers located in the corenetwork to support QOS routing and accelerate the reservation process ofthe new path. The hyper operator overlay network (HO-OL) 510 can alsoaddress other related policy issues such as security and AAA(authentication, authorization, accounting), and the like, which aregenerally not easy for one operator. The hyper operator overlay network(HO-OL) 510 can also provide a signaling path so that the architectureis easy to implement.

Thus, QOS support systems are shown using a hyper operator overly(HO-OL) architecture or a distributed architecture. The architecturesinclude vertical handover gateways (HO-GW) 208 to support seamlessvertical handovers. The frameworks can support varying handoverrequirements in terms of delay, loss and bandwidth by choosing an MPLSpath. The frameworks can also account for the adaptation ability of theapplication layer by allowing the application to specify the QOSrequirements after considering the applications mechanisms. The networkcan then provide necessary adaptation ability and avoid duplicatefunctionalities. The frameworks support different applications.

While the invention has been described above by reference to variousembodiments, it will be understood that many changes and modificationscan be made without departing from the scope of the invention. It istherefore intended that the foregoing detailed description be understoodas an illustration of the presently preferred embodiments of theinvention, and not as a definition of the invention. It is only thefollowing claims, including all equivalents, which are intended todefine the scope of this invention.

1. A method for supporting handover between heterogeneous networks,comprising: establishing a first reservation path; establishing ahandover path to accommodate a quality of service property; performingadmission control that considers the established handover paths and thefirst reservation path; contacting gateways to determine a handover pathto use to support quality of service (QoS) during a vertical handover;using the determined handover path to support the vertical handover; andestablishing a second reservation path while maintaining the firstreservation path and the determined handover path.
 2. The method ofclaim 1 wherein the handover path comprises MPLS paths.
 3. The method ofclaim 2 wherein the MPLS paths accommodate more than one quality ofservice property.
 4. The method of claim 1 wherein an access routercontacts the gateway.
 5. The method of claim 4 wherein the access routerinforms the gateway of a destination administration domain.
 6. Themethod of claim 1 wherein the vertical handover comprises a verticalhandover between base stations under different administration domains.7. The method of claim 1 wherein the determination comprises querying adatabase.
 8. The method of claim 1 further including contacting gatewayswith a hyper operator.
 9. The method of claim 1 wherein at least one ofthe first and second reservation paths comprise an RSVP path.
 10. Asystem for supporting handover between a mobile host and a correspondingnode in a heterogeneous network, comprising: a first reservation path toconnect the mobile host and the corresponding node; a handover path toaccommodate a quality of service property; an admission controlapplication that considers the established handover paths and the firstreservation path; a gateway to determine a handover path to use tosupport quality of service (QoS) during a vertical handover, wherein thedetermined handover path is used to support vertical handover; and asecond reservation path to connect the mobile host and the correspondingnode, the second reservation path being established while maintainingthe first reservation path and the handover path.
 11. The system ofclaim 10 wherein the handover path comprises MPLS paths.
 12. The systemof claim 11 wherein the MPLS paths accommodate more than one quality ofservice property.
 13. The system of claim 10 further including an accessrouter, wherein the access router contacts the gateway to determine ahandover path to use.
 14. The system of claim 13 wherein the accessrouter informs the gateway of a destination administration domain. 15.The system of claim 10 wherein the vertical handover comprises avertical handover between bases stations under different administrationdomains.
 16. The system of claim 10 further comprising a database,wherein the determined handover path is established by querying thedatabase.
 17. The system of claim 10 further including a hyper operatorwherein the hyper operator contacts the gateways.
 18. The system ofclaim 10 wherein at least one of the first and second reservation pathscomprise an RSVP path.